Workers in electrical installation and service fields have long used multi-meters for testing, measuring, or monitoring electrical current and potentials. When first introduced it consisted of a low current DC meter mounted in a rugged case with a complex switching arrangement using precision wire wound resisters, or shunts across, or in series. Such meters are now even more versatile. With a rectifier meters are both AC and DC with various ranges. By switching a dry cell battery in series with proper values it will check resistance values or continuity by using a reverse scale on the meter face. A multi-meter now is a most basic and essential instrument and allows the user to read, for example, AC and DC voltages and current, resistance, capacity, inductance, dBm, and frequency, all with two color coded test leads, and to test or check everything from small electronic components such as diodes, transistors or printed circuits, to larger apparatus such as panels, controllers, moving machinery panels, or large electrical structures. Few of the latter types of structures are tested under ideal conditions and can present many hazards to the user of a multi-meter.
For example, using a multi-meter standing on a ladder is not easy. The user may often wish for more than two hands. One hand may be required simply to hang on or adjust a safety harness. The physical hazards can be much worse such as hundreds of feet in the air on an antenna or transmission tower or mast. Many such structures are designed to sway or move. On a tower or mast of a ship at sea the swaying or movement can be extreme. Also, control panels may be dark, complicated and with close quarters, and full of high voltage lines, relays and other moving parts. Often times a multi-meter user needs a helper if for no other reason than to hold a flashlight or take notes.
Such meters may be used in wall cavities or in an engine compartment, under the dash, or even under a car. If the electrical panel is on a moving train or vehicle the situation becomes even more difficult.
One of the most important items used with any multi-meter is the test leads. Today test leads come with a variety of tips and accessories. Many are made with different plastic compounds and come in various lengths. The test lead in measuring voltage, resistance and current flow is usually not considered important. One common problem is the length of wire on most test leads. The wire usually dangles, wraps around other objects, or just gets in the way, and most users have learned to put up with lead problems.
Any person who has used a meter over any length of time has encountered the problems noted above by dropping or burning out meters, by putting the probe inadvertently into hot or moving equipment, or by tangling the probe lead. The cost of the problem in time, meters and equipment is extraordinary.
It would accordingly be advantageous if a multi-meter user could take full advantage of the instrument without the problems noted above.